Allow wp_mail to set Sender field when setting From

[bastho]

[38287] forces PHPMailer's setFrom() to don't set Sender field.

It seems to improve compatibility on some server environments, but it's a regression on those which support -f option. On these ones, the Sender is something like www-data@host which can cause SPF failure if the server name doesn't match the domain name (which occurs pretty often).

While this setting is very dependent of the server environment, I suggest to add a constant WP_MAIL_AUTO_SENDER to determine the expected behavior.

[SergeyBiryukov]

Hi @bastho, thanks for the ticket and the patch!

We're already tracking this issue in #25239.